EP3319906B1 - Sio2 containing dispersion with high salt stability - Google Patents

Sio2 containing dispersion with high salt stability Download PDF

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Publication number
EP3319906B1
EP3319906B1 EP16733472.1A EP16733472A EP3319906B1 EP 3319906 B1 EP3319906 B1 EP 3319906B1 EP 16733472 A EP16733472 A EP 16733472A EP 3319906 B1 EP3319906 B1 EP 3319906B1
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Prior art keywords
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silica
dispersion
modified
atom
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German (de)
French (fr)
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EP3319906A1 (en
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Wolfgang Lortz
Ulrich Fischer
Christian Panz
Gabriele BERGMANN
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Evonik Operations GmbH
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Evonik Operations GmbH
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/146—After-treatment of sols
    • C01B33/149—Coating
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/141—Preparation of hydrosols or aqueous dispersions
    • C01B33/1415—Preparation of hydrosols or aqueous dispersions by suspending finely divided silica in water
    • C01B33/1417—Preparation of hydrosols or aqueous dispersions by suspending finely divided silica in water an aqueous dispersion being obtained
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/157—After-treatment of gels
    • C01B33/159—Coating or hydrophobisation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability

Definitions

  • the invention relates to SiO 2 -containing dispersions with high salt stability, their production and use.
  • US2004241101 discloses a stable pharmaceutical dispersion containing silicon dioxide particles surface-modified with polyethylene glycols.
  • the latter can be obtained, for example, by reacting an ammonia-stabilized colloidal silicon dioxide with a polyethoxylated trialkoxysilane.
  • the US2002172827 deals, among other things, with the production of redispersible, nanoscale silicon dioxide particles.
  • a negatively charged silica sol is coated with an aluminum oxide.
  • Sodium dodecylbenzenesulfonate is then added as a surface-modifying agent.
  • WO2004035474 A process is claimed for the production of a stable, aqueous dispersion which is obtained by mixing silanized, colloidal silicon dioxide particles with an organic binder.
  • a glycidyl epoxysilane for example, serves as the silanizing agent.
  • the organic binder can be a polyethylene glycol.
  • colloidal silicon dioxide particles are surface-modified with 2- [methoxy (polyethylenoxy) propyl] trimethoxysilane in order to increase the salt stability.
  • a precipitated silica which has a BET surface area of 150-400 m 2 / g, a CTAB surface area of 140-350 m 2 / g and an Al 2 O 3 content of 0.2-5% by weight .
  • This silica can be modified with a variety of silanes and lead to hydrophilic as well as hydrophobic products.
  • the ratio of silane to precipitated silica can also be varied over wide limits, namely 0.5 to 50 parts of silane, based on 100 parts of precipitated silica.
  • the reaction can take place in the dispersion of the precipitated silica, with subsequent drying and tempering. Conditions for this are not specified, and the properties of the dispersion are not specified further.
  • a method for priming steel in which an aqueous, alumina-silica sol with 0.05-2.0 wt .-% alumina is used.
  • the alumina-silica sol may contain a silane coupling agent containing alkoxysilane groups and an organic residue having a functional group such as an amino, epoxide or isocyanate.
  • WO2010 / 042672 discloses a coating composition for thermoplastic and thermoset substrates comprising an aqueous dispersion having a pH of less than 7.5. This contains surface-modified silica nanoparticles with an average particle diameter of 40 nm or less, an alkoxysilane oligomer and a silane coupling agent. Suitable surface modifiers are those which have a radical that can react with the silanol groups on the silicon dioxide surface, and a hydrophilic radical, for example an acid radical, an ammonium radical, a polyoxyethylene radical or a hydroxyl group.
  • US 2004/037964 A1 discloses a method of priming steel and the coating materials therefor. Coatings are described which contain an Al-stabilized silica sol which can be modified with organosilanes. Particle size of the silica sol particles can be 3-100 nm. The pH of the dispersion can be more than 8. As a silica source, only silica sols and optionally alkali metal silicates are explicitly mentioned, but no pyrogenic silicas.
  • US 2005/133766 A1 discloses aqueous dispersions containing at least two different types of particles with an average particle size of less than 100 ā‡ m, which are stable to sedimentation.
  • Dispersions US 2005/133766 A1 can contain pyrogenic and surface-modified silicas and can be a mixture of silica and aluminum dioxide particles, but not Al-modified silica particles. Salt stability of the dispersions is shown in US 2005/133766 A1 not addressed.
  • aqueous dispersion of the present invention a 0.5 percent by weight aqueous dispersion in a reference solution simulating seawater is stable for at least one month at a temperature of 60.degree. The stability is tested in a reference solution which is obtained by adding at 23 Ā° C.
  • the proportion of Al in the surface-modified, hydrophilic silica is 0.15 mg Al / m 2 BET surface area. 0.05-0.15 mg Al / m 2 BET surface area is particularly preferred.
  • Such particles are obtained from pyrogenic processes prior to surface modification.
  • silicon compounds are converted in a flame, generated by the reaction of hydrogen and oxygen.
  • the powders obtained in this way are referred to as ā€œpyrogenicā€ or ā€œfumedā€.
  • highly dispersed primary particles are initially formed, which grow together to form aggregates in the further course of the reaction.
  • the aggregate dimensions of these powders are usually in the ā‡ m range.
  • the particles have hydroxyl groups on the surface. By suitable grinding, these can be converted into the nm range which is advantageous for the present invention and subsequently treated with a surface modifier.
  • the surface-modified, hydrophilic silica can be in the form of isolated individual particles and / or in the form of aggregated particles.
  • the mean particle diameter describes the dimensions of the aggregate.
  • the surface-modified, hydrophilic silica present in the aqueous dispersion according to the invention is characterized, inter alia, in that the surface modification comprises a hydrocarbon radical which is bonded to a Si atom via a carbon atom.
  • the hydrocarbon residue is to be selected so that the surface-modified Silica has hydrophilic properties in the aqueous dispersion. This depends, for example, on the number of carbon atoms in the hydrocarbon radical and the presence of functional, hydrophilic groups such as hydroxyl, ether, amine or carboxyl groups.
  • the hydrocarbon radical is preferably interrupted by one or more heteroatoms. The heteroatom of O or N is particularly preferred.
  • the carbon content of the surface-modified, hydrophilic silica is preferably 3 to 25% by weight.
  • the proportion of water is preferably 50-90% by weight and of surface-modified, hydrophilic silica is preferably 10-50% by weight. Depending on the planned further use, the proportion of surface-modified, hydrophilic silica can be further reduced.
  • the liquid phase can also contain small amounts of alcohol, such as methanol, ethanol, propanol or butanol.
  • alcohol such as methanol, ethanol, propanol or butanol.
  • the proportion of alcohol is generally less than 10% by weight, preferably 3-7% by weight, based in each case on the dispersion.
  • the pH of the liquid phase of the dispersion is 8 or more, preferably 8-12, particularly preferably 9-11.
  • the aqueous dispersion according to the invention can contain small amounts, less than 100 ppm, of customary dispersants. However, the presence of dispersants is not desirable in the context of the present invention.
  • the stabilizing effect of the dispersion according to the invention is due solely to the surface-modified, hydrophilic silica.
  • the aqueous dispersion can be prepared by a method in which a hydrophilic silica, which has hydroxyl groups on the surface, is dispersed in an aqueous solvent and then an agent for surface modification is added, in which a Si atom is attached to a carbon atom Hydrocarbon radical and the Si atom is further bonded to one or more hydroxyl groups, alkoxy groups, halide groups or mixtures thereof, and the mixture reacts and optionally separates the hydrolysis product.
  • the amount of surface modifying agent depends on the desired ratio of silica to surface modifying agent.
  • the carbon content of the surface-modified silica proves to be a suitable variable. This is preferably 3 to 25% by weight.
  • the amount of hydroxyl groups, alkoxy groups or halide groups split off during the hydrolysis must be taken into account.
  • a number of methods are available to the person skilled in the art for dispersion.
  • Devices such as ultrasonic probes, ball mills, agitator ball mills, rotor / stator machines, planetary kneaders / mixers or high-energy mills or combinations are available for the production of finely divided dispersions.
  • a rotor / stator system can be used to produce a predispersion which is further ground in a subsequent step using a high-energy mill. This combination enables, for example, extra fine dispersions with a particle diameter of 200 nm or less to be produced.
  • a high-energy mill a high-pressure pre-dispersion is divided into two or more streams, which are then expanded through a nozzle and meet exactly.
  • the mixture is reacted by setting a pH value of 11 or more, thermally treating the mixture at a temperature of 50-95 Ā° C. for a period of 1-30 minutes and then optionally adjusting the pH from 8 - 10.
  • the silica used in the process is one in which there are hydroxyl groups on the surface.
  • a pyrogenic silica is used.
  • silicon is also intended to include mixed oxides and doped silicas, the main constituent of which is more than 50% by weight, better than 90% by weight, preferably more than 99% by weight , Is silicon dioxide.
  • Suitable mixed oxide components are, for example, Al or Ti.
  • a Si-Al mixed oxide in which an Al atom is part of the particle surface and whose weight ratio Al 2 O 3 / SiO 2 is 0.1: 99.9-5:95 is particularly suitable .
  • silicas doped with alkali metal in particular with potassium
  • the potassium content calculated as K 2 O, is 0.005-5% by weight, the BET surface area from 100 to 350 m 2 / g.
  • Such silicas are for example in WO2008 / 071462 , EP1216956 or WO2006 / 134014 disclosed. These silicas have a very low degree of aggregation and are easy to disperse despite their high BET surface area.
  • Y comprises branched polyethylene glycols.
  • the surface modification agent can particularly preferably be selected from the group consisting of (CH 3 O) 3 Si (CH 2 ) 3 -OCH 3 , (CH 3 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 3 -OCH 3 , (CH 3 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 6-9 -OCH 3 , (CH 3 O) 3 (CH 2 ) 3 - (OCH 2 CH 2 ) 9-12 - OCH 3 , (CH 3 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 21-24 -OCH 3 and (CH 3 CH 2 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 8-12 OH must be selected.
  • Aqueous compositions are also suitable for surface modification, the organopolysiloxanes with glycidether alkyl radicals, acryloxyalkyl radicals and / or Contain methacryloxyalkyl radicals.
  • the organopolysiloxane can contain aminoalkyl radicals or alkyl radicals or aminoalkyl and alkyl radicals as further functional groups.
  • Each silicon in the organopolysiloxane preferably carries a functional group.
  • the organopolysiloxane-containing compositions preferably have a pH of 1-8, particularly preferably 3-6.
  • a readily redispersible, surface-modified powder can be obtained from the aqueous dispersion according to the invention by separating off the liquid phase, for example by spray drying.
  • This powder can be incorporated into an aqueous phase by means of low energy input, for example by stirring, without any noticeable aggregation of the particles occurring.
  • the particle diameter in this dispersion can be between 40 and 200 nm.
  • the BET surface area of the surface-modified, hydrophilic silica is 40-500 m 2 / g, particularly preferably 80-300 m 2 / g.
  • the BET surface area is determined in accordance with DIN 66131.
  • aqueous dispersion according to the invention and the surface-modified, hydrophilic silica resulting therefrom can each be used as a component of pharmaceutical preparations, cosmetic preparations, water-based paints and varnishes, cleaning agents, dishwashing detergents and coating colors in the paper industry.
  • AERODISPĀ® W 7512 S, Evonik Industries is an acidic, low-viscosity, aqueous silica dispersion with a solids content of 12%.
  • the underlying solid is AEROSILĀ® 200, Evonik Industries, a pyrogenic silica with a BET surface area of 200 m 2 / g.
  • AERODISPĀ® W7520 N Evonik Industries
  • AERODISPĀ® W7520 N Evonik Industries
  • the underlying solid is AEROSILĀ® 200, Evonik Industries, a pyrogenic silica with a BET surface area of 200 m 2 / g.
  • AERODISPĀ® W 7330 N Evonik Industries
  • AERODISPĀ® W 7330 N Evonik Industries
  • the underlying solid is AEROSILĀ® 130, Evonik Industries, a pyrogenic silica with a BET surface area of 130 m 2 / g.
  • AERODISPĀ® W 7320 N Evonik Industries
  • AERODISPĀ® W 7320 N Evonik Industries
  • the underlying solid is AEROSILĀ® 130, Evonik Industries, a pyrogenic silica with a BET surface area of 130 m 2 / g.
  • the potassium-doped silica corresponds to example P1 from WO2008 / 071462 . It has a BET surface area of 216 m2 / g. The K content is 0.12% by weight, calculated as K 2 O. After the addition has ended, the suction nozzle is closed and sheared at 3000 rpm for 20 minutes.
  • the dispersion is diluted with 20 kg of water and the pH is adjusted to 10.0 with sodium hydroxide solution. It is then diluted with water in order to achieve an SiO 2 content of 25% by weight and sheared again for about 5 minutes for the purpose of homogenization.
  • AERODISPĀ® W 630 Evonik Industries
  • AERODISPĀ® W 630 Evonik Industries
  • AERODISPĀ® W 630 Evonik Industries
  • the underlying solid is AEROXIDEĀ® Alu C, Evonik Industries, a pyrogenic aluminum oxide with a BET surface area of 100 m 2 / g.
  • Sodium aluminate solution 10% by weight, produced from anhydrous technical grade sodium aluminate, Sigma-Aldrich, and deionized water. A few insoluble residues are removed by filtration.
  • LUDOXĀ® SM 30, Grace is an aqueous, NaOH-stabilized, colloidal silica dispersion with a particle size of 8 nm and a SiO 2 content of 30% by weight.
  • LUDOXĀ® HS 40 is an aqueous, NaOH-stabilized, colloidal silica dispersion with a particle size of 12 nm and an SiO 2 content of 40% by weight.
  • LUDOXĀ® CL Grace, is an aqueous dispersion of Al-coated, colloidal silica with a particle size of 22 nm.
  • the pH is 3.5-4.5, the solids content 39-43% by weight.
  • aqueous dispersions according to the invention of Examples 1-4 have very good stability in the reference solution at elevated temperatures. This stability is not given in Comparative Examples 5-13.

Description

Die Erfindung betrifft SiO2 enthaltende Dispersionen mit hoher SalzstabilitƤt, deren Herstellung und Verwendung.The invention relates to SiO 2 -containing dispersions with high salt stability, their production and use.

Die Verbesserung der StabilitƤt von wƤsserigen Siliciumdioxid-Dispersionen ist Gegenstand der Forschung. Gewƶhnlich wird versucht Ć¼ber eine geeignete OberflƤchenmodifizierung der Siliciumdioxidpartikel die Dispersion vor Sedimentation und Reagglomeration zu schĆ¼tzen.The improvement of the stability of aqueous silicon dioxide dispersions is the subject of research. An attempt is usually made to protect the dispersion from sedimentation and reagglomeration by means of a suitable surface modification of the silicon dioxide particles.

So wird beispielsweise in US2004241101 eine stabile pharmazeutische Dispersion offenbart, die mit Polyethylenglykolen oberflƤchenmodifizierte Siliciumdioxidpartikel enthƤlt. Letztere kƶnnen beispielsweise erhalten werden, indem man ein mit Ammoniak stabilisiertes kolloidales Siliciumdioxid mit einem polyethoxylierten Trialkoxysilan zur Reaktion bringt.For example, in US2004241101 discloses a stable pharmaceutical dispersion containing silicon dioxide particles surface-modified with polyethylene glycols. The latter can be obtained, for example, by reacting an ammonia-stabilized colloidal silicon dioxide with a polyethoxylated trialkoxysilane.

Die US2002172827 beschƤftigt sich unter anderem mit der Herstellung redispergierbarer, nanoskaliger Siliciumdioxidpartikel. Dabei wird ein negativ geladenes Silicasol mit einem Aluminiumoxid beschichtet. Nachfolgend wird als oberflƤchennmodifizierendes Mittel Natriumdodecylbenzolsulfonat zugegeben.the US2002172827 deals, among other things, with the production of redispersible, nanoscale silicon dioxide particles. A negatively charged silica sol is coated with an aluminum oxide. Sodium dodecylbenzenesulfonate is then added as a surface-modifying agent.

In WO2004035474 wird ein Verfahren zur Herstellung einer stabilen, wƤssrigen Dispersion beansprucht, die durch Mischen von silanisierten, kolloidalen Siliciumdioxidpartikeln mit einem organischen Bindemittel erhalten wird. Als Silanisierungsmittel dient beispielsweise ein Glycidylepoxysilan. Das organische Bindemittel kann ein Polyethylenglykol sein.In WO2004035474 A process is claimed for the production of a stable, aqueous dispersion which is obtained by mixing silanized, colloidal silicon dioxide particles with an organic binder. A glycidyl epoxysilane, for example, serves as the silanizing agent. The organic binder can be a polyethylene glycol.

In Particle and Particle Systems Characterization 2014, 31(1), 94-100 werden kolloidale Siliciumdioxidpartikel mit 2-[Methoxy(polyethylenoxy)propyl]trimethoxysilan oberflƤchenmodifiziert um die SalzstablitƤt zu erhƶhen.In Particle and Particle Systems Characterization 2014, 31 (1), 94-100 colloidal silicon dioxide particles are surface-modified with 2- [methoxy (polyethylenoxy) propyl] trimethoxysilane in order to increase the salt stability.

In der WO03/106339 wird eine FƤllungskieselsƤure beschrieben, die eine BET-OberflƤche von 150 - 400 m2/g, eine CTAB-OberflƤche von 140 - 350 m2/g und einen Al2O3-Gehalt von 0,2 - 5 Gew.-% aufweist. Diese KieselsƤure kann mit einer Vielzahl von Silanen modifiziert werden und zu hydrophilen als auch zu hydrophoben Produkten fĆ¼hren. Auch das VerhƤltnis Silan zu FƤllungskieselsƤure kann Ć¼ber weite Grenzen variiert werden, nƤmlich 0.5 bis 50 Teile Silan, bezogen auf 100 Teile FƤllungskieselsƤure. Die Reaktion kann in der Dispersion der FƤllungskieselsƤure erfolgen, mit anschlieƟender Trocknung und Temperung. Bedingungen hierzu werden nicht genannt, die Eigenschaften der Dispersion nicht weiter spezifiziert.In the WO03 / 106339 a precipitated silica is described which has a BET surface area of 150-400 m 2 / g, a CTAB surface area of 140-350 m 2 / g and an Al 2 O 3 content of 0.2-5% by weight . This silica can be modified with a variety of silanes and lead to hydrophilic as well as hydrophobic products. The ratio of silane to precipitated silica can also be varied over wide limits, namely 0.5 to 50 parts of silane, based on 100 parts of precipitated silica. The reaction can take place in the dispersion of the precipitated silica, with subsequent drying and tempering. Conditions for this are not specified, and the properties of the dispersion are not specified further.

In WO02/22745 wird ein Verfahren zum Grundieren von Stahl offenbart, bei dem ein wƤssriges, Aluminiumoxid-Siliciumdioxid-Sol mit 0,05-2,0 Gew.-% Aluminiumoxid eingesetzt wird. Das Aluminiumoxid-Siliciumdioxid-Sol kann ein Silan-Kupplungsmittel enthalten, das Alkoxysilan-Gruppen und einen organischen Rest mit einer funktionelle Gruppe, wie eine Amino, Epoxid oder Isocyanat enthƤlt.In WO02 / 22745 a method for priming steel is disclosed in which an aqueous, alumina-silica sol with 0.05-2.0 wt .-% alumina is used. The alumina-silica sol may contain a silane coupling agent containing alkoxysilane groups and an organic residue having a functional group such as an amino, epoxide or isocyanate.

In WO2010/042672 wird eine Beschichtungszusammensetzung fĆ¼r thermoplastische und duroplastische Substrate offenbart, umfassend eine wƤssrige Dispersion mit einem pH-Wert von weniger als 7,5. Diese enthƤlt oberflƤchenmodifizierte Siliciumdioxid-Nanoteilchen, mit einem mittleren Teilchendurchmesser von 40 nm oder weniger, ein Alkoxysilan-Oligomer und ein Silan-Kupplungsmittel. Als OberflƤchenmodifizierungsmittel kommen solche in Frage, die einen Rest aufweisen, der mit den Silanolgruppen auf der SiliciumdioxidoberflƤche reagieren kann, sowie einen hydrophilen Rest, beispielsweise einen SƤurerest, eine Ammoniumrest, einen Polyoxyethylenrest oder eine Hydroxylgruppe.In WO2010 / 042672 discloses a coating composition for thermoplastic and thermoset substrates comprising an aqueous dispersion having a pH of less than 7.5. This contains surface-modified silica nanoparticles with an average particle diameter of 40 nm or less, an alkoxysilane oligomer and a silane coupling agent. Suitable surface modifiers are those which have a radical that can react with the silanol groups on the silicon dioxide surface, and a hydrophilic radical, for example an acid radical, an ammonium radical, a polyoxyethylene radical or a hydroxyl group.

US 2004/037964 A1 offenbart ein Verfahren zur Grundierung von Stahl und die Beschichtungsmaterialien dafĆ¼r. Es werden Beschichtungen beschrieben, die ein Al-stabilisiertes Silicasol enthalten, das mit Organosilanen modifiziert sein kann. PartikelgrĆ¶ĆŸe der Silicasol Partikel kann 3-100 nm betragen. Der pH-Wert der Dispersion kann mehr als 8 sein. Als Silica-Quelle, werden explizit nur Silica-Sole und optional Alkalimetallsilikate erwƤhnt, aber keine pyrogenen KieselsƤuren. US 2004/037964 A1 discloses a method of priming steel and the coating materials therefor. Coatings are described which contain an Al-stabilized silica sol which can be modified with organosilanes. Particle size of the silica sol particles can be 3-100 nm. The pH of the dispersion can be more than 8. As a silica source, only silica sols and optionally alkali metal silicates are explicitly mentioned, but no pyrogenic silicas.

US 2005/133766 A1 offenbart wƤssrige Dispersionen enthaltend wenigstens zwei unterschiedliche Partikeltypen mit einer mittleren PartikelgrĆ¶ĆŸe von kleiner 100 Āµm, die stabil gegenĆ¼ber der Sedimentation sind. Dispersionen aus US 2005/133766 A1 kƶnnen pyrogene und oberflƤchenmodifizierte KieselsƤuren enthalten und kƶnnen ein Gemisch von Silica und Aluminiumdioxidpartikeln darstellen, aber keine mit Al-modifizierten Silicapartikel. SalzstabilitƤt der Dispersionen wird in US 2005/133766 A1 nicht thematisiert. US 2005/133766 A1 discloses aqueous dispersions containing at least two different types of particles with an average particle size of less than 100 Ī¼m, which are stable to sedimentation. Dispersions US 2005/133766 A1 can contain pyrogenic and surface-modified silicas and can be a mixture of silica and aluminum dioxide particles, but not Al-modified silica particles. Salt stability of the dispersions is shown in US 2005/133766 A1 not addressed.

Es hat sich jedoch gezeigt, dass fĆ¼r etliche Anwendungen die erreichte SalzstabilitƤt nicht ausreichend ist. Aufgabe der vorliegenden Erfindung war es daher eine Dispersion bereitzustellen, die eine verbesserte SalzstabilitƤt aufweist.It has been shown, however, that the salt stability achieved is not sufficient for a number of applications. It was therefore an object of the present invention to provide a dispersion which has improved salt stability.

Gegenstand der Erfindung ist eine wƤsserige Dispersion enthaltend Partikel einer oberflƤchenmodifizierten, pyrogenen hydrophilen KieselsƤure, wobei

  1. A) die Partikel der oberflƤchenmodifizierten, hydrophilen KieselsƤure ein Aluminiumatom und einen Kohlenwasserstoffrest umfassen,
    1. a) das Aluminiumatom Ć¼ber ein Sauerstoffatom an ein Siliciumatom der PartikeloberflƤche gebunden ist,
    2. b) der Kohlenwasserstoffrest ein Siliciumatom umfasst, welches an ein Kohlenstoffatom des Kohlenwasserstoffrestes gebunden ist,
    3. c) einen mittleren Partikeldurchmesser dso in der Dispersion von 40 - 200 nm, bevorzugt 60 - 150 nm, besitzen und
  2. B) der pH-Wert der Dispersion 8 oder mehr ist.
The invention relates to an aqueous dispersion containing particles of a surface-modified, pyrogenic hydrophilic silica, wherein
  1. A) the particles of the surface-modified, hydrophilic silica comprise an aluminum atom and a hydrocarbon radical,
    1. a) the aluminum atom is bound to a silicon atom of the particle surface via an oxygen atom,
    2. b) the hydrocarbon radical comprises a silicon atom which is bonded to a carbon atom of the hydrocarbon radical,
    3. c) have an average particle diameter d 50 in the dispersion of 40-200 nm, preferably 60-150 nm, and
  2. B) the pH of the dispersion is 8 or more.

Unter oberflƤchenmodifiziert ist zu verstehen, dass die KieselsƤure an ihrer OberflƤche Gruppen trƤgt, die den Partikeln weitestgehend die hydrophilen Eigenschaften verleiht, die die nicht modifizierte KieselsƤure aufweist. Hierdurch bleibt die wƤsserige Dispersion stabil. Stabil soll heiƟen, dass keine nennenswerte Reagglomeration und damit keine Sedimentation erfolgen. Hydrophobierten Partikel wĆ¼rden in einer wƤsserigen Lƶsung in kĆ¼rzester Zeit reagglomerieren und separieren.Surface-modified is to be understood as meaning that the silica carries groups on its surface which give the particles as far as possible the hydrophilic properties that the unmodified silica has. As a result, the aqueous dispersion remains stable. Should be stable mean that there is no significant reagglomeration and thus no sedimentation. Water-repellent particles would reaglomerate and separate in a very short time in an aqueous solution.

Diese StabilitƤt soll auch in wƤsserigen Lƶsungen mit einer hohen Salzkonzentration und bei erhƶhten Temperaturen erhalten bleiben. FĆ¼r die wƤsserige Dispersion der vorliegenden Erfindung gilt, dass eine 0,5 gewichtsprozentige wƤsserige Dispersion in einer, Seewasser simulierenden, Referenzlƶsung wenigstens einen Monat bei einer Temperatur von 60Ā°C stabil ist. Die Testung der StabilitƤt erfolgt in einer Referenzlƶsung, die erhalten wird, indem man bei 23Ā°C zu einem Gemisch aus 28,500 g NaCl, 0,220 g NaHCO3, 4,066 g Na2SO4, 1,625 g CaCl2 x 2 H2O, 3,162 g MgCl2 x 6 H2O, 0,024 g SrCl2 x 6 H2O und 0, 721 g KCl so viel vollentsalztes Wasser gibt, bis man 1000 ml Lƶsung enthƤlt.This stability should also be retained in aqueous solutions with a high salt concentration and at elevated temperatures. For the aqueous dispersion of the present invention, a 0.5 percent by weight aqueous dispersion in a reference solution simulating seawater is stable for at least one month at a temperature of 60.degree. The stability is tested in a reference solution which is obtained by adding at 23 Ā° C. to a mixture of 28.500 g NaCl, 0.220 g NaHCO 3 , 4.066 g Na 2 SO 4 , 1.625 g CaCl 2 Ɨ 2 H 2 O, 3.162 g MgCl 2 x 6 H 2 O, 0.024 g SrCl 2 x 6 H 2 O and 0.721 g KCl add enough deionized water to contain 1000 ml of the solution.

In einer bevorzugten AusfĆ¼hrungsform der Erfindung ist der Anteil an AI in der oberflƤchenmodifizierten, hydrophilen KieselsƤure ā‰¤0,15 mg Al/m2 BET-OberflƤche ist. Besonders bevorzugt ist 0,05 - 0,15 mg Al/m2 BET-OberflƤche.In a preferred embodiment of the invention, the proportion of Al in the surface-modified, hydrophilic silica is 0.15 mg Al / m 2 BET surface area. 0.05-0.15 mg Al / m 2 BET surface area is particularly preferred.

Solche Partikel werden, vor der OberflƤchenmodifizierung, aus pyrogenen Prozessen erhalten. Dabei werden Siliciumverbindungen in einer Flamme, erzeugt durch die Reaktion von Wasserstoff und Sauerstoff, umgesetzt. Die so erhaltenen Pulver werden als "pyrogen" oder "fumed" bezeichnet. Bei der Reaktion werden zunƤchst hochdisperse PrimƤrpartikel gebildet, die im weiteren Reaktionsverlauf zu Aggregaten zusammenwachsen. Die Aggregatdimensionen dieser Pulver sind in der Regel im Āµm-Bereich. Die Partikel weisen an der der OberflƤche Hydroxylgruppen auf. Durch geeignete Vermahlung kƶnnen diese in den fĆ¼r die vorliegende Erfindung vorteilhaften nm-Bereich Ć¼berfĆ¼hrt werden und nachfolgend mit einem OberflƤchenmodifizierungsmittel behandelt werden.Such particles are obtained from pyrogenic processes prior to surface modification. Here, silicon compounds are converted in a flame, generated by the reaction of hydrogen and oxygen. The powders obtained in this way are referred to as "pyrogenic" or "fumed". During the reaction, highly dispersed primary particles are initially formed, which grow together to form aggregates in the further course of the reaction. The aggregate dimensions of these powders are usually in the Āµm range. The particles have hydroxyl groups on the surface. By suitable grinding, these can be converted into the nm range which is advantageous for the present invention and subsequently treated with a surface modifier.

Es hat sich gezeigt, dass die besten Ergebnisse bezĆ¼glich der Salz- und TemperaturstabilitƤt der wƤsserigen Dispersion mit einer oberflƤchenmodifizierten, hydrophilen KieselsƤure erhalten werden, welche in der Dispersion, einen mittleren Partikeldurchmesser d50 von 40 - 200 nm aufweist. Der mittlere Partikeldurchmesser kann mit den Ć¼blichen dem Fachmann bekannten Methoden der Lichtstreuung zur Bestimmung von TeilchengrĆ¶ĆŸenverteilungen in Dispersionen bestimmt werden.It has been shown that the best results with regard to the salt and temperature stability of the aqueous dispersion are obtained with a surface-modified, hydrophilic silica which, in the dispersion, has an average particle diameter d 50 of 40-200 nm. The mean particle diameter can be determined using the usual methods of light scattering known to the person skilled in the art for determining particle size distributions in dispersions.

Die oberflƤchenmodifizierte, hydrophile KieselsƤure kann in Form isolierter Einzelpartikel und/oder in Form von aggregierten Partikeln vorliegen. Im Falle von aggregierten Partikeln beschreibt der mittlere Partikeldurchmesser die Dimension des Aggregates.The surface-modified, hydrophilic silica can be in the form of isolated individual particles and / or in the form of aggregated particles. In the case of aggregated particles, the mean particle diameter describes the dimensions of the aggregate.

Die in der erfindungsgemƤƟen wƤsserigen Dispersion vorliegende oberflƤchenmodifizierte, hydrophile KieselsƤure ist unter anderem dadurch gekennzeichnet, dass die OberflƤchenmodifizierung einen Kohlenwasserstoffrest umfasst, der Ć¼ber ein C-Atom an ein Si-Atom gebunden ist. Dier Kohlenwasserstoffrest ist so zu wƤhlen, dass die oberflƤchenmodifizierte KieselsƤure in der wƤsserigen Dispersion hydrophile Eigenschaften aufweist. Dies ist beispielsweise von der Anzahl der Kohlenstoffatome des Kohlenwasserstoffrestes und dem Vorhandensein von funktionellen, hydrophilen Gruppen, wie Hydroxy-, Ether-, Amin- oder Carboxylgruppen abhƤngig. Bevorzugt ist der Kohlenwasserstoffrest durch ein oder mehrere Heteroatome unterbrochen. Besonders bevorzugt ist das Heteroatom des O oder N ist.The surface-modified, hydrophilic silica present in the aqueous dispersion according to the invention is characterized, inter alia, in that the surface modification comprises a hydrocarbon radical which is bonded to a Si atom via a carbon atom. The hydrocarbon residue is to be selected so that the surface-modified Silica has hydrophilic properties in the aqueous dispersion. This depends, for example, on the number of carbon atoms in the hydrocarbon radical and the presence of functional, hydrophilic groups such as hydroxyl, ether, amine or carboxyl groups. The hydrocarbon radical is preferably interrupted by one or more heteroatoms. The heteroatom of O or N is particularly preferred.

Der Kohlenstoffgehalt der oberflƤchenmodifizierten, hydrophilen KieselsƤure betrƤgt bevorzugt 3 - 25 Gew.-%.The carbon content of the surface-modified, hydrophilic silica is preferably 3 to 25% by weight.

Bevorzugt wird eine OberflƤchenmodifizierung aus der Gruppe bestehend aus Si-(CH2)n-Ym-R ausgewƤhlt, wobei Si das Si-Atom ist, welches Ć¼ber ein C-Atom an einen Kohlenwasserstoffrest gebunden ist, und

  • n = 1, 2, 3 und m= 0, 1
  • R ein Rest ist, der keine hydrophobe Eigenschaften verleiht, und bevorzugt fĆ¼r den Fall, dass m = 1 ist
  • R = -H, -CH3, -C2H5, -OH, -OCH3, -OC2H5, -C(=O)OCH3, -C(=O)OC2H5, -O-C(=O)CH3, -O-C(=O)CH3, -O-C(=O)CH=CH2, -O-C(=O)CH=CH(CH3), -C(=O)CH3, -C(=O)H, NH2;
    Figure imgb0001
     und fĆ¼r den Fall, dass m=0 ist, R den vorgenannten Resten entspricht, jedoch ohne -H, -CH3, -C2H5.
  • Y = -(OCR1R2-CR3R4)o-, o = 1 - 30, R1, R2, R3, R4= unabhƤngig voneinander H oder CH3,
    • besonders bevorzugt o = 5 - 15 und R1, R2, R3, R4= H;
    • -(OCR1R2-CR3R4-CR5R6)p- , p = 1 - 30, R1, R2, R3, R4, R5, R6= unabhƤngig
  • oder ein Gemisch der vorgenannten Reste R und Y ist.
A surface modification is preferably selected from the group consisting of Si- (CH 2 ) n ā€”Y m ā€”R, where Si is the Si atom which is bonded to a hydrocarbon radical via a C atom, and
  • n = 1, 2, 3 and m = 0, 1
  • R is a radical which does not impart any hydrophobic properties, and is preferred in the event that m = 1
  • R = -H, -CH 3 , -C 2 H 5 , -OH, -OCH 3 , -OC 2 H 5 , -C (= O) OCH 3 , -C (= O) OC 2 H 5 , -OC (= O) CH 3 , -OC (= O) CH 3 , -OC (= O) CH = CH 2 , -OC (= O) CH = CH (CH 3 ), -C (= O) CH 3 , -C (= O) H, NH 2 ;
    Figure imgb0001
     and in the event that m = 0, R corresponds to the aforementioned radicals, but without -H, -CH 3 , -C 2 H 5 .
  • Y = - (OCR 1 R 2 -CR 3 R 4 ) o -, o = 1 - 30, R 1 , R 2 , R 3 , R 4 = independently of one another H or CH 3 ,
    • particularly preferably o = 5-15 and R 1 , R 2 , R 3 , R 4 = H;
    • - (OCR 1 R 2 -CR 3 R 4 -CR 5 R 6 ) p -, p = 1 - 30, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 = independent
  • or a mixture of the aforementioned radicals R and Y is.

In der erfindungsgemƤƟen wƤsserigen Dispersion betrƤgt der Anteil an Wasser bevorzugt 50 - 90 Gew.-% und an oberflƤchenmodifizierter, hydrophiler KieselsƤure bevorzugt 10 - 50 Gew.-%. Je nach der geplanten weiteren Verwendung kann der Anteil an oberflƤchenmodifizierter, hydrophiler KieselsƤure weiter reduziert werden.In the aqueous dispersion according to the invention, the proportion of water is preferably 50-90% by weight and of surface-modified, hydrophilic silica is preferably 10-50% by weight. Depending on the planned further use, the proportion of surface-modified, hydrophilic silica can be further reduced.

Die flĆ¼ssige Phase kann neben Wasser noch geringe Anteile von Alkohol, wie Methanol, Ethanol, Propanol oder Butanol enthalten. Der Anteil an Alkohol betrƤgt in der Regel weniger als 10 Gew.-%, bevorzugt 3 - 7 Gew.-%, jeweils bezogen auf die Dispersion.In addition to water, the liquid phase can also contain small amounts of alcohol, such as methanol, ethanol, propanol or butanol. The proportion of alcohol is generally less than 10% by weight, preferably 3-7% by weight, based in each case on the dispersion.

Der pH-Wert der flĆ¼ssigen Phase der Dispersion betrƤgt 8 oder mehr, bevorzugt 8 -12, besonders bevorzugt 9 - 11.The pH of the liquid phase of the dispersion is 8 or more, preferably 8-12, particularly preferably 9-11.

Die erfindungsgemƤƟe wƤsserige Dispersion kann geringe Mengen, weniger als 100 ppm, an Ć¼blichen Dispergiermitteln enthalten. Die Anwesenheit von Dispergiermitteln ist im Rahmen der vorliegenden Erfindung jedoch nicht gewĆ¼nscht. Der stabilisierende Effekt der erfindungsgemƤƟen Dispersion liegt allein in der oberflƤchenmodifizierten, hydrophilen KieselsƤure begrĆ¼ndet.The aqueous dispersion according to the invention can contain small amounts, less than 100 ppm, of customary dispersants. However, the presence of dispersants is not desirable in the context of the present invention. The stabilizing effect of the dispersion according to the invention is due solely to the surface-modified, hydrophilic silica.

Die wƤssrige Dispersion kann durch ein Verfahren hergestellt werden, bei dem man eine hydrophile KieselsƤure, welche an der OberflƤche Hydroxylgruppen aufweist, in einem wƤsserigen Lƶsungsmittel dispergiert und nachfolgend ein Mittel zur OberflƤchenmodifizierung hinzufĆ¼gt, bei dem ein Si-Atom Ć¼ber ein C-Atom an einen Kohlenwasserstoffrest und das Si-Atom weiterhin an ein oder mehrere Hydroxygruppen, Alkoxygruppen, Halogenidgruppen oder Mischungen daraus gebunden ist, und das Gemisch zur Reaktion bringt und gegebenenfalls das Hydrolyseprodukt abtrennt.The aqueous dispersion can be prepared by a method in which a hydrophilic silica, which has hydroxyl groups on the surface, is dispersed in an aqueous solvent and then an agent for surface modification is added, in which a Si atom is attached to a carbon atom Hydrocarbon radical and the Si atom is further bonded to one or more hydroxyl groups, alkoxy groups, halide groups or mixtures thereof, and the mixture reacts and optionally separates the hydrolysis product.

Die Menge des OberflƤchenmodifizierungmittels richtet sich nach dem gewĆ¼nschten VerhƤltnis von KieselsƤure zu OberflƤchenmodifizierungmittel. Als geeignete GrĆ¶ĆŸe erweist sich der Kohlenstoffanteil der oberflƤchenmodifizierten KieselsƤure. Dieser ist bevorzugt 3 - 25 Gew.-%. Dabei ist die Menge der bei der Hydrolyse abgespaltenen Hydroxygruppen, Alkoxygruppen oder Halogenidgruppen zu berĆ¼cksichtigen.The amount of surface modifying agent depends on the desired ratio of silica to surface modifying agent. The carbon content of the surface-modified silica proves to be a suitable variable. This is preferably 3 to 25% by weight. The amount of hydroxyl groups, alkoxy groups or halide groups split off during the hydrolysis must be taken into account.

Zur Dispergierung stehen dem Fachmann etliche Methoden zur VerfĆ¼gung. Zur Herstellung feinteiliger Dispersionen stehen beispielsweise Vorrichtungen wie Ultraschallsonden, KugelmĆ¼hlen, RĆ¼hrwerkskugelmĆ¼hlen, Rotor-/Statormaschinen, Planetenkneter/-mixer oder HochenergiemĆ¼hlen oder Kombinationen zur VerfĆ¼gung. So kann beispielsweise mittels eines Rotor-/Statorsystems eine Vordispersion hergestellt werden, die in einem nachfolgend Schritt mittels einer HochenergiemĆ¼hle weiter vermahlen wird. Durch diese Kombination kƶnnen beispielsweise extra feine Dispersionen mit einem Partikeldurchmesser von 200 nm oder weniger hergestellt werden. Bei einer HochenergiemĆ¼hle wird eine unter einem hohen Druck stehende Vordispersion in zwei oder mehrere Strƶme geteilt, die dann Ć¼ber eine DĆ¼se entspannt werden und exakt aufeinandertreffen.A number of methods are available to the person skilled in the art for dispersion. Devices such as ultrasonic probes, ball mills, agitator ball mills, rotor / stator machines, planetary kneaders / mixers or high-energy mills or combinations are available for the production of finely divided dispersions. For example, a rotor / stator system can be used to produce a predispersion which is further ground in a subsequent step using a high-energy mill. This combination enables, for example, extra fine dispersions with a particle diameter of 200 nm or less to be produced. In a high-energy mill, a high-pressure pre-dispersion is divided into two or more streams, which are then expanded through a nozzle and meet exactly.

Es hat sich als vorteilhaft erwiesen, die KieselsƤure bereits in Form einer wƤsserigen Dispersion einzubringen.It has proven advantageous to introduce the silica in the form of an aqueous dispersion.

In der Regel wird das Gemisch zur Reaktion gebracht, indem man einen pH-Wert von 11 oder mehr einstellt, das Gemisch bei einer Temperatur von 50 - 95Ā°C Ć¼ber einen Zeittraum von 1 - 30 Minuten thermisch behandelt und nachfolgend gegebenenfalls einen pH-Wert von 8 - 10 einstellt.As a rule, the mixture is reacted by setting a pH value of 11 or more, thermally treating the mixture at a temperature of 50-95 Ā° C. for a period of 1-30 minutes and then optionally adjusting the pH from 8 - 10.

Bei der im Verfahren eingesetzten KieselsƤure handelt es sich um eine, bei der an der OberflƤche Hydroxylgruppen vorliegen. Es wird eine pyrogene KieselsƤure eingesetzt.The silica used in the process is one in which there are hydroxyl groups on the surface. A pyrogenic silica is used.

Im Rahmen der vorliegenden Erfindung soll der Begriff "KieselsƤure" auch Mischoxide und dotierte KieselsƤuren umfassen, deren Hauptbestandteil mit einem Anteil von mehr als 50 Gew.-%, besser mehr als 90 Gew.-%, am besten mehr als 99 Gew.-%, Siliciumdioxid ist.
Geeignete Mischoxidkomponenten sind beispielsweise AI oder Ti. Besonders geeignet ist ein Si-Al-Mischoxid, bei dem ein Al-Atom Bestandteil der PartikeloberflƤche ist und dessen GewichtsverhƤltnis Al2O3/SiO2 0,1:99,9 - 5:95 ist.In the context of the present invention, the term "silica" is also intended to include mixed oxides and doped silicas, the main constituent of which is more than 50% by weight, better than 90% by weight, preferably more than 99% by weight , Is silicon dioxide.
Suitable mixed oxide components are, for example, Al or Ti. A Si-Al mixed oxide in which an Al atom is part of the particle surface and whose weight ratio Al 2 O 3 / SiO 2 is 0.1: 99.9-5:95 is particularly suitable .

Weiterhin kƶnnen mit Alkalimetall, insbesondere mit Kalium, dotierte KieselsƤuren eingesetzt werden. Der Anteil an Kalium, gerechnet als K2O, betrƤgt 0,005-5 Gew.-%, die BET-OberflƤche von 100 bis 350 m2/g. Solche KieselsƤuren sind beispielsweise in WO2008/071462 , EP1216956 oder WO2006/134014 offenbart. Diese KieselsƤuren weisen einen sehr niedrigen Aggregrationsgrad auf und sind trotz hoher BET-OberflƤche leicht zu dispergieren.Furthermore, silicas doped with alkali metal, in particular with potassium, can be used. The potassium content, calculated as K 2 O, is 0.005-5% by weight, the BET surface area from 100 to 350 m 2 / g. Such silicas are for example in WO2008 / 071462 , EP1216956 or WO2006 / 134014 disclosed. These silicas have a very low degree of aggregation and are easy to disperse despite their high BET surface area.

FĆ¼r das Verfahren wird das Mittel zur OberflƤchenmodifizierung bevorzugt aus der Gruppe bestehend aus X4-a[Si-(CH2)n-Ym-R]a ausgewƤhlt, mit

  • a = 1,2,3; bevorzugt a = 1; n = 1, 2, 3; m = 0, 1,
  • X = H, OH, OCH3, OC2H5, OCH2CH2H3, OCH(CH3)2; Cl,
  • Y = -(OCR1R2-CR3R4)o-, o = 1 - 30, R1, R2, R3, R4 = unabhƤngig voneinander H oder CH3, besonders bevorzugt o = 5 - 15 und R1, R2, R3, R4 = H;
    -(OCR1R2-CR3R4-CR5R6)p- , p = 1 - 30, R1, R2, R3, R4, R5, R6 = unabhƤngig voneinander H oder CH3,
  • R ein Rest ist, der keine hydrophobe Eigenschaften verleiht, und bevorzugt fĆ¼r den Fall, dass m = 1 ist
  • R = -H, -CH3, -C2H5, -OH, -OCH3, -OC2H5, -C(=O)OCH3, -C(=O)OC2H5, -O-C(=O)CH3, -O-C(=O)CH3, -O-C(=O)CH=CH2, -O-C(=O)CH=CH(CH3), -C(=O)CH3, -C(=O)H, NH2;
    Figure imgb0002
     und fĆ¼r den Fall, dass m=0 ist, R den vorgenannten Resten entspricht, jedoch ohne -H, -CH3, -C2H5.
  • Y = -(OCR1R2-CR3R4)o-, o = 1 - 30, R1, R2, R3, R4= unabhƤngig voneinander H oder CH3, besonders bevorzugt o = 5 - 15 und R1, R2, R3, R4 = H;
    -(OCR1R2-CR3R4-CR5R6)p- , p = 1 - 30, R1, R2, R3, R4, R5, R6= unabhƤngig
  • oder ein Gemisch der vorgenannten Reste R und Y ist.
For the method, the surface modification agent is preferably selected from the group consisting of X 4-a [Si (CH 2 ) n -Y m -R] a , with
  • a = 1,2,3; preferably a = 1; n = 1, 2, 3; m = 0, 1,
  • X = H, OH, OCH 3 , OC 2 H 5 , OCH 2 CH 2 H 3 , OCH (CH 3 ) 2 ; Cl,
  • Y = - (OCR 1 R 2 -CR 3 R 4 ) o -, o = 1-30, R 1 , R 2 , R 3 , R 4 = independently of one another H or CH 3 , particularly preferably o = 5-15 and R 1 , R 2 , R 3 , R 4 = H;
    - (OCR 1 R 2 -CR 3 R 4 -CR 5 R 6 ) p -, p = 1-30, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 = independently of one another H or CH 3 ,
  • R is a radical which does not impart any hydrophobic properties, and is preferred in the event that m = 1
  • R = -H, -CH 3 , -C 2 H 5 , -OH, -OCH 3 , -OC 2 H 5 , -C (= O) OCH 3 , -C (= O) OC 2 H 5 , -OC (= O) CH 3 , -OC (= O) CH 3 , -OC (= O) CH = CH 2 , -OC (= O) CH = CH (CH 3 ), -C (= O) CH 3 , -C (= O) H, NH 2 ;
    Figure imgb0002
     and in the event that m = 0, R corresponds to the aforementioned radicals, but without -H, -CH 3 , -C 2 H 5 .
  • Y = - (OCR 1 R 2 -CR 3 R 4 ) o -, o = 1-30, R 1 , R 2 , R 3 , R 4 = independently of one another H or CH 3 , particularly preferably o = 5-15 and R 1 , R 2 , R 3 , R 4 = H;
    - (OCR 1 R 2 -CR 3 R 4 -CR 5 R 6 ) p -, p = 1 - 30, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 = independent
  • or a mixture of the aforementioned radicals R and Y is.

Es ist ebenso denkbar, dass Y verzweigte Polyethylenglykole umfasst. Hierbei stellt R und wenigstens einer der Reste R1-R6 eine -(OCH2-CH2)r-Gruppierung dar, mit r = 5 - 15.It is also conceivable that Y comprises branched polyethylene glycols. Here, R and at least one of the radicals R 1 -R 6 represents a - (OCH 2 -CH 2 ) r grouping, with r = 5-15.

Besonders bevorzugt kann das Mittel zur OberflƤchenmodifizierung aus der Gruppe bestehend aus (CH3O)3Si(CH2)3-OCH3, (CH3O)3Si(CH2)3-(OCH2CH2)3-OCH3, (CH3O)3Si(CH2)3-(OCH2CH2)6-9-OCH3, (CH3O)3(CH2)3-(OCH2CH2)9-12-OCH3, (CH3O)3Si(CH2)3-(OCH2CH2)21-24-OCH3 und (CH3CH2 O)3Si(CH2)3-(OCH2CH2)8-12OH ausgewƤhlt sein.The surface modification agent can particularly preferably be selected from the group consisting of (CH 3 O) 3 Si (CH 2 ) 3 -OCH 3 , (CH 3 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 3 -OCH 3 , (CH 3 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 6-9 -OCH 3 , (CH 3 O) 3 (CH 2 ) 3 - (OCH 2 CH 2 ) 9-12 - OCH 3 , (CH 3 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 21-24 -OCH 3 and (CH 3 CH 2 O) 3 Si (CH 2 ) 3 - (OCH 2 CH 2 ) 8-12 OH must be selected.

Weiterhin kann das Mittel zur OberflƤchenmodifizierung aus der Gruppe bestehend aus (RO)3Si-(CH2)3-NH2,(RO)3Si-(CH2)3-CH-CH2-NH2, (RO)3Si-(CH2)3-NH-(CH2)2-NH2, (RO)3Si-(CH2)3-NH-(CH2)2NH(CH2)-NH2, (RO)3Si-(CH2)3-N-[(CH2)2NH(CH2)-NH2]2, R= CH3, C2H5, ausgewƤhlt sein.Furthermore, the surface modification agent can be selected from the group consisting of (RO) 3 Si- (CH 2 ) 3 -NH 2 , (RO) 3 Si- (CH 2 ) 3 -CH-CH 2 -NH 2 , (RO) 3 Si- (CH 2 ) 3 -NH- (CH 2 ) 2 -NH 2 , (RO) 3 Si- (CH 2 ) 3 -NH- (CH 2 ) 2 NH (CH 2 ) -NH 2 , (RO) 3 Si (CH 2 ) 3 -N - [(CH 2 ) 2 NH (CH 2 ) -NH 2 ] 2 , R = CH 3 , C 2 H 5 .

Weiterhin sind zur OberflƤchenmodifizierung wƤsserige Zusammensetzungen geeignet, die Organopolysiloxane mit Glycidetheralkylresten, Acryloxyalkylresten und/oder Methacryloxyalkylresten enthalten. Weiterhin kann das Organopolysiloxan als weitere funktionelle Gruppen Aminoalkyl-Reste oder Alkyl-Reste oder Aminoalkyl- und Alkyl-Rest enthalten. Vorzugsweise trƤgt dabei jedes Silicium im Organopolysiloxan eine funktionelle Gruppe. Die organopolysiloxanhaltige Zusammensetzungen kƶnnen erhalten werden durch Mischen wasserlƶslicher Organosilane der Formel I

ā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒH2N(CH2)f(NH)g(CH2)i-Si(CH3)h(OR)3-hā€ƒā€ƒā€ƒā€ƒā€ƒ(I),

wobei 0 ā‰¤ f ā‰¤ 6, g = 0 falls f = 0, g =1 falls f >1, 0 ā‰¤ i ā‰¤ 6, 0 ā‰¤ h ā‰¤ 1 und R eine Methyl-, Ethyl-, Propyl- oder Isopropyl-Gruppe sind, bevorzugt Aminopropyltriethoxysilan,
mit
wasserlƶslichen, jedoch in wƤsserigem Medium nicht stabilen Organosilanen der Formel II

ā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒX-CH2O(CH2)3-Si(CH3)h(OR)3-hā€ƒā€ƒā€ƒā€ƒā€ƒ(II),

wobei 0 ā‰¤ h ā‰¤1 ist und R einen Methyl-, Ethyl-, Propyl- oder Isopropyl-Rest darstellt, bevorzugt Glycidyloxypropyltrimethoxysilan und X =

Figure imgb0003
und/oder
Organosilanen der Formel III

ā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒH2C=CR'-COO(CH2)3-Si(CH3)h(OR)3-hā€ƒā€ƒā€ƒā€ƒā€ƒ(III),

wobei 0 ā‰¤ h ā‰¤ 1 ist, R einen Methyl-, Ethyl-, Propyl- oder Isopropyl-Rest und R' einen Methyl- oder Wasserstoff-Rest darstellen, bevorzugt Methacryloxypropyltrimethoxysilan,
und nicht wasserlƶslichen Organosilanen der Formel IV

ā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒR"-Si(CH3)h(OR)3-hā€ƒā€ƒā€ƒā€ƒā€ƒ(IV),

wobei 0 ā‰¤ h ā‰¤ 1 ist, R einen Methyl-, Ethyl-, Propyl- oder Isopropyl-Rest und R" einen linearen, verzweigten oder cyclischen Kohlenwasserstoff-Rest mit 1 bis 8 C-Atomen darstellen, bevorzugt Propyltrimethoxysilan,
in dem molaren VerhƤltnis M = a/(b+c+d), wobei a die Summe der Molzahlen der Organosilane gemƤƟ Formel I, b die Summe der Molzahlen der Organosilane gemƤƟ Formel II sowie c die Summe der Molzahlen der Organosilane gemƤƟ Formel III und d die Summe der Molzahlen der Organosilane gemƤƟ Formel IV sind, mit 0 ā‰¤ M ā‰¤ 3 und mindestens b > 0 oder c > 0. Das Gemisch wird mit einem Wasser/SƤure-Gemisch versetzt, der pH-Wert der Reaktionsmischung auf einen Wert zwischen 1 und 8 eingestellt und der Alkohol entfernt.Aqueous compositions are also suitable for surface modification, the organopolysiloxanes with glycidether alkyl radicals, acryloxyalkyl radicals and / or Contain methacryloxyalkyl radicals. Furthermore, the organopolysiloxane can contain aminoalkyl radicals or alkyl radicals or aminoalkyl and alkyl radicals as further functional groups. Each silicon in the organopolysiloxane preferably carries a functional group. The organopolysiloxane-containing compositions can be obtained by mixing water-soluble organosilanes of the formula I

H 2 N (CH 2 ) f (NH) g (CH 2 ) i -Si (CH 3 ) h (OR) 3-h (I),

where 0 f 6, g = 0 if f = 0, g = 1 if f> 1, 0 i 6, 0 h 1 and R is a methyl, ethyl, propyl or isopropyl group , preferably aminopropyltriethoxysilane,
with
organosilanes of the formula II which are soluble in water but not stable in an aqueous medium

X-CH 2 O (CH 2 ) 3 -Si (CH 3 ) h (OR) 3-h (II),

where 0 h 1 and R represents a methyl, ethyl, propyl or isopropyl radical, preferably glycidyloxypropyltrimethoxysilane and X =
Figure imgb0003
 and or
Organosilanes of the formula III

H 2 C = CR'-COO (CH 2 ) 3 -Si (CH 3 ) h (OR) 3-h (III),

where 0 ā‰¤ h ā‰¤ 1, R is a methyl, ethyl, propyl or isopropyl radical and R 'is a methyl or hydrogen radical, preferably methacryloxypropyltrimethoxysilane,
and water-insoluble organosilanes of the formula IV

R "-Si (CH 3 ) h (OR) 3-h (IV),

where 0 ā‰¤ h ā‰¤ 1, R represents a methyl, ethyl, propyl or isopropyl radical and R "represents a linear, branched or cyclic hydrocarbon radical with 1 to 8 carbon atoms, preferably propyltrimethoxysilane,
in the molar ratio M = a / (b + c + d), where a is the sum of the moles of the organosilanes according to formula I, b is the sum of the moles of the organosilanes according to formula II and c is the sum of the moles of the organosilanes according to formula III and d are the sum of the number of moles of the organosilanes according to formula IV, with 0 M 3 and at least b> 0 or c> 0. The mixture is mixed with a water / acid mixture, the pH of the reaction mixture to a value between 1 and 8 are set and the alcohol is removed.

Die organopolysiloxanhaltigen Zusammensetzungen kƶnnen idealisiert dargestellt werden gemƤƟ der Formel

ā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒā€ƒHO[Si(A*)(OH)z(CH3)1-zO]a[Si(B*)(OH)y(CH3)1-yO]b[Si(C*)(OH)w(CH3)1-wO]c[Si(D*)(OH)v(CH3)1-vO]dH(HX)eā€ƒā€ƒā€ƒā€ƒā€ƒ(V)

  • wobei A* einen Aminoalkyl-Rest abgeleitet aus der Formel I,
  • B* einen Glycidetheralkyl-Rest abgeleitet aus der Formel II,
  • C* einen Acryloxyalkyl- oder Methacryloxyalkyl-Rest abgeleitet aus der Formel III und
  • D* einen Alkyl-Rest gemƤƟ der allgemeinen Formel IV bedeuten,
  • HX eine SƤure darstellt, wobei X ein anorganischer oder organischer SƤure-Rest ist,
  • v gleich 0 oder 1 und w gleich 0 oder 1 und y gleich 0 oder 1 und z gleich 0 oder 1 und a+b+c+d ā‰„ 4 und a ā‰¤ e ā‰¤ 2 a sind, mit 0 ā‰¤ a/(b+c+d) ā‰¤ 3, genĆ¼gen.
The organopolysiloxane-containing compositions can be idealized according to the formula

HO [Si (A *) (OH) z (CH 3 ) 1-z O] a [Si (B *) (OH) y (CH 3 ) 1-y O] b [Si (C *) (OH) w (CH 3 ) 1-w O] c [Si (D *) (OH) v (CH 3 ) 1-v O] d H (HX) e (V)

  • where A * is an aminoalkyl radical derived from the formula I,
  • B * a glycidetheralkyl radical derived from the formula II,
  • C * is an acryloxyalkyl or methacryloxyalkyl radical derived from the formula III and
  • D * is an alkyl radical according to the general formula IV,
  • HX represents an acid, where X is an inorganic or organic acid residue,
  • v is 0 or 1 and w is 0 or 1 and y is 0 or 1 and z is 0 or 1 and a + b + c + d ā‰„ 4 and a ā‰¤ e ā‰¤ 2 a, with 0 ā‰¤ a / (b + c + d) ā‰¤ 3, suffice.

Die organopolysiloxanhaltigen Zusammensetzungen weisen bevorzugt einen pH-Wert von 1 - 8, besonders bevorzugt von 3 - 6 auf.The organopolysiloxane-containing compositions preferably have a pH of 1-8, particularly preferably 3-6.

Aus der erfindungsgemƤƟen wƤsserigen Dispersion kann durch Abtrennen der flĆ¼ssigen Phase, beispielsweise durch SprĆ¼htrocknung, ein leicht redispergierbares, oberflƤchenmodifiziertes Pulver erhalten werden. Dieses Pulver kann durch geringen Energieeintrag, beispielsweise durch RĆ¼hren, in eine wƤsserige Phase eingearbeitet werden, ohne dass es zu einer bemerkenswerten Aggregation der Partikel kommt. Die Partikeldurchmesser in dieser Dispersion kƶnnen bei 40 - 200 nm liegen.A readily redispersible, surface-modified powder can be obtained from the aqueous dispersion according to the invention by separating off the liquid phase, for example by spray drying. This powder can be incorporated into an aqueous phase by means of low energy input, for example by stirring, without any noticeable aggregation of the particles occurring. The particle diameter in this dispersion can be between 40 and 200 nm.

So entsteht eine oberflƤchenmodifizierte, hydrophile KieselsƤure, die

  1. a) ein Aluminiumatom aufweist, welches Ć¼ber ein Sauerstoffatom an ein Siliciumatom der PartikeloberflƤche gebunden ist,
  2. b) ein Kohlenwasserstoffrest enthƤlt, der ein Siliciumatom umfasst, welches an ein Kohlenstoffatom des Kohlenwasserstoffrestes gebunden ist,
  3. c) eine BET-OberflƤche von 40 - 500 m2/g aufweist und
  4. d) einen mittleren Partikeldurchmesser dso in der Dispersion von 40 - 200 nm, bevorzugt 60 - 150 nm, besitzt und
  5. e) eine OberflƤchenmodifizierung aufweist, ausgewƤhlt aus der Gruppe bestehend aus Si-(CH2)n-Ym-R ist, wobei Si das Si-Atom ist, welches Ć¼ber ein C-Atom an einen Kohlenwasserstoffrest gebunden ist, und
    • n = 1, 2, 3; m = 0, 1,
    • X = H, OH, OCH3, OC2H5, Cl,
    • Y = -(OCR1R2-CR3R4)o-, o = 1 - 30, R1, R2, R3, R4= unabhƤngig voneinander H oder CH3, -(OCR1R2-CR3R4-CR5R6)p- , p = 1 - 30, R1, R2, R3, R4, R5, R6 = unabhƤngig voneinander H oder CH3,
      R ein Rest ist, der keine hydrophobe Eigenschaften verleiht, und bevorzugt fĆ¼r den Fall, dass m = 1 ist
  • R = -H, -CH3, -C2H5, -OH, -OCH3, -OC2H5, -C(=O)OCH3, -C(=O)OC2H5, -O-C(=O)CH3, -O-C(=O)CH3, -O-C(=O)CH=CH2, -O-C(=O)CH=CH(CH3), -C(=O)CH3, -C(=O)H, NH2;
    Figure imgb0004
     und fĆ¼r den Fall, dass m=0 ist, R den vorgenannten Resten entspricht, jedoch ohne -H, -CH3, -C2H5.
  • Y = -(OCR1R2-CR3R4)o-, o = 1 - 30, R1, R2, R3, R4 = unabhƤngig voneinander H oder CH3, besonders bevorzugt o = 5 - 15 und R1, R2, R3, R4 = H;
    -(OCR1R2-CR3R4-CR5R6)p- , p = 1 - 30, R1, R2, R3, R4, R5, R6= unabhƤngig oder ein Gemisch der vorgenannten Reste R und Y ist
This creates a surface-modified, hydrophilic silica that
  1. a) has an aluminum atom which is bonded to a silicon atom of the particle surface via an oxygen atom,
  2. b) contains a hydrocarbon radical which comprises a silicon atom which is bonded to a carbon atom of the hydrocarbon radical,
  3. c) has a BET surface area of 40-500 m 2 / g and
  4. d) has an average particle diameter d 50 in the dispersion of 40-200 nm, preferably 60-150 nm, and
  5. e) has a surface modification selected from the group consisting of Si- (CH 2 ) n -Y m -R, where Si is the Si atom which is bonded to a hydrocarbon radical via a C atom, and
    • n = 1, 2, 3; m = 0, 1,
    • X = H, OH, OCH 3 , OC 2 H 5 , Cl,
    • Y = - (OCR 1 R 2 -CR 3 R 4 ) o -, o = 1 - 30, R 1 , R 2 , R 3 , R 4 = independently of one another H or CH 3 , - (OCR 1 R 2 -CR 3 R 4 -CR 5 R 6 ) p -, p = 1 - 30, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 = independently of one another H or CH 3 ,
      R is a radical which does not impart any hydrophobic properties, and is preferred in the event that m = 1
  • R = -H, -CH 3 , -C 2 H 5 , -OH, -OCH 3 , -OC 2 H 5 , -C (= O) OCH 3 , -C (= O) OC 2 H 5 , -OC (= O) CH 3 , -OC (= O) CH 3 , -OC (= O) CH = CH 2 , -OC (= O) CH = CH (CH 3 ), -C (= O) CH 3 , -C (= O) H, NH 2 ;
    Figure imgb0004
     and in the event that m = 0, R corresponds to the aforementioned radicals, but without -H, -CH 3 , -C 2 H 5 .
  • Y = - (OCR 1 R 2 -CR 3 R 4 ) o -, o = 1-30, R 1 , R 2 , R 3 , R 4 = independently of one another H or CH 3 , particularly preferably o = 5-15 and R 1 , R 2 , R 3 , R 4 = H;
    - (OCR 1 R 2 -CR 3 R 4 -CR 5 R 6 ) p -, p = 1-30, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 = independently or a mixture of the aforementioned Radicals R and Y is

Die BET-OberflƤche der oberflƤchenmodifizierten, hydrophilen KieselsƤure betrƤgt 40 - 500 m2/g, besonders bevorzugt 80 - 300 m2/g. Die BET-OberflƤche wird bestimmt nach DIN 66131.The BET surface area of the surface-modified, hydrophilic silica is 40-500 m 2 / g, particularly preferably 80-300 m 2 / g. The BET surface area is determined in accordance with DIN 66131.

Die erfindungsgemƤƟe wƤsserige Dispersion und die daraus resultierende oberflƤchenmodifizierte, hydrophile KieselsƤure kann jeweils als Bestandteil von pharmazeutischen Zubereitungen, kosmetischen Zubereitungen, wasserbasierender Farbe und Lacke, von Reinigungsmitteln, von GeschirrspĆ¼lmitteln und von Streichfarben in der Papierindustrie verwendet werden.The aqueous dispersion according to the invention and the surface-modified, hydrophilic silica resulting therefrom can each be used as a component of pharmaceutical preparations, cosmetic preparations, water-based paints and varnishes, cleaning agents, dishwashing detergents and coating colors in the paper industry.

BeispieleExamples SalzstabilitƤt bei 60Ā°CSalt stability at 60 Ā° C

In 900 g voll entsalztem Wasser (VE-Wasser) werden 28,500 g NaCl, 0,220 g NaHCO3, 4,066 g Na2SO4, 1,625 g CaCl2 x 2 H2O, 3,162 g MgCl2 x 6 H2O, 0,024 g SrCl2 x 6 H2O, 0, 721 g KCl gelƶst und mit VE-Wasser auf 1 Liter aufgefĆ¼llt.
99,5 g dieser Lƶsung werden in einer 125 ml Weithalsflaschen aus NALGENEĀ® FEP (Tetrafluorethylen-Hexafluorpropylen-Copolymer; Thermo Scientifc) vorgelegt und 0,5 g der zu prĆ¼fenden Dispersion hinzugegeben und durch SchĆ¼tteln homogenisiert. Das Gemisch wird bei 60Ā°C im Trockenschrank gelagert und das Auftreten eines Niederschlages visuell kontrolliert. 28.500 g of NaCl, 0.220 g of NaHCO 3 , 4.066 g of Na 2 SO 4 , 1.625 g of CaCl 2 Ɨ 2 H 2 O, 3.162 g of MgCl 2 Ɨ 6 H 2 O, 0.024 g are added to 900 g of fully demineralized water (deionized water) SrCl 2 x 6 H 2 O, 0.721 g of KCl dissolved and made up to 1 liter with deionized water.
99.5 g of this solution are placed in a 125 ml wide neck bottle made of NALGENEĀ® FEP (tetrafluoroethylene-hexafluoropropylene copolymer; Thermo Scientifc) and 0.5 g of the dispersion to be tested is added and homogenized by shaking. The mixture is stored at 60 Ā° C. in a drying cabinet and the occurrence of a precipitate is checked visually.

EinsatzstoffeInput materials

AERODISPĀ® W 7512 S, Evonik Industries, ist eine saure, niedrigviskose, wƤssrige KieselsƤure-Dispersion mit einem Feststoffgehalt von 12 %. Der zugrundeliegende Feststoff ist AEROSILĀ® 200, Evonik Industries, eine pyrogene KieselsƤure mit einer BET-OberflƤche von 200 m2/g.AERODISPĀ® W 7512 S, Evonik Industries, is an acidic, low-viscosity, aqueous silica dispersion with a solids content of 12%. The underlying solid is AEROSILĀ® 200, Evonik Industries, a pyrogenic silica with a BET surface area of 200 m 2 / g.

AERODISPĀ® W7520 N, Evonik Industries, ist eine mit Natronlauge stabilisierte, niedrigviskose, wƤssrige KieselsƤure-Dispersion mit einem Feststoffgehalt von 20%. Der zugrundeliegende Feststoff ist AEROSILĀ® 200, Evonik Industries, eine pyrogene KieselsƤure mit einer BET-OberflƤche von 200 m2/g.AERODISPĀ® W7520 N, Evonik Industries, is a sodium hydroxide stabilized, low-viscosity, aqueous silica dispersion with a solids content of 20%. The underlying solid is AEROSILĀ® 200, Evonik Industries, a pyrogenic silica with a BET surface area of 200 m 2 / g.

AERODISPĀ® W 7330 N, Evonik Industries, ist eine mit Natronlauge stabilisierte, wƤssrige KieselsƤure-Dispersion mit einem Feststoffgehalt von 30%. Der zugrundeliegende Feststoff ist AEROSILĀ® 130, Evonik Industries, eine pyrogene KieselsƤure mit einer BET-OberflƤche von 130 m2/g.AERODISPĀ® W 7330 N, Evonik Industries, is an aqueous silica dispersion stabilized with sodium hydroxide solution with a solids content of 30%. The underlying solid is AEROSILĀ® 130, Evonik Industries, a pyrogenic silica with a BET surface area of 130 m 2 / g.

AERODISPĀ® W 7320 N, Evonik Industries, ist eine mit Natronlauge stabilisierte, wƤssrige KieselsƤure-Dispersion mit einem Feststoffgehalt von 20%. Der zugrundeliegende Feststoff ist AEROSILĀ® 130, Evonik Industries, eine pyrogene KieselsƤure mit einer BET-OberflƤche von 130 m2/g.AERODISPĀ® W 7320 N, Evonik Industries, is an aqueous silica dispersion stabilized with sodium hydroxide solution with a solids content of 20%. The underlying solid is AEROSILĀ® 130, Evonik Industries, a pyrogenic silica with a BET surface area of 130 m 2 / g.

Dispersion von kalium-dotierter KieselsƤureDispersion of potassium-doped silica

In einem 100 I Edelstahl-AnsatzbehƤlter werden 45,0 kg Wasser vorgelegt. AnschlieƟend werden mit Hilfe des SaugrĆ¼ssels der Ystral Conti-TDS 3 (Statorschlitze: 4 mm Kranz und 1 mm Kranz, Rotor/Stator-Abstand ca. 1 mm) unter Scherbedingungen 30 kg kalium-dotierte KieselsƤure eingesaugt. Die kalium-dotierte KieselsƤure entspricht Beipiel P1 aus WO2008/071462 . Sie weist eine BET-OberflƤche von 216 m2/g. Der K-Anteil betrƤgt 0,12 Gew.-%, berechnet als K2O. Nach Beendigung der Zugabe wird der Einsaugstutzen geschlossen und noch bei 3000 U/min 20 min lang nachgeschert. Mit 20 kg Wasser wird die Dispersion verdĆ¼nnt und mit Natronlauge der pH-Wert 10,0 eingestellt. AnschlieƟend wird mit Wasser verdĆ¼nnt um einen SiO2-Gehalt von 25 Gew.-% zu erreichen und noch einmal ca. 5 Minuten zwecks Homogenisierung nachgeschert.45.0 kg of water are placed in a 100 l stainless steel batch container. Then, with the aid of the suction pipe of the Ystral Conti-TDS 3 (stator slots: 4 mm ring and 1 mm ring, rotor / stator distance approx. 1 mm), 30 kg of potassium-doped silica are applied under shear conditions sucked in. The potassium-doped silica corresponds to example P1 from WO2008 / 071462 . It has a BET surface area of 216 m2 / g. The K content is 0.12% by weight, calculated as K 2 O. After the addition has ended, the suction nozzle is closed and sheared at 3000 rpm for 20 minutes. The dispersion is diluted with 20 kg of water and the pH is adjusted to 10.0 with sodium hydroxide solution. It is then diluted with water in order to achieve an SiO 2 content of 25% by weight and sheared again for about 5 minutes for the purpose of homogenization.

AERODISPĀ® W 630, Evonik Industries, ist eine wƤssrige Aluminiumoxid-Dispersion mit einem pH-wert von 3 - 5 und einem Feststoffgehalt von 30%. Der zugrundeliegende Feststoff ist AEROXIDEĀ® Alu C, Evonik Industries, eine pyrogenes Aluminiumoxid mit einer BET-OberflƤche von 100 m2/g.AERODISPĀ® W 630, Evonik Industries, is an aqueous aluminum oxide dispersion with a pH of 3 - 5 and a solids content of 30%. The underlying solid is AEROXIDEĀ® Alu C, Evonik Industries, a pyrogenic aluminum oxide with a BET surface area of 100 m 2 / g.

Natriumaluminatlƶsung, 10 Gew.-%, hergestellt wasserfreiem technischem Natriumaluminat, Sigma-Aldrich, und VE-Wasser. Einige wenige unlƶsliche RĆ¼ckstƤnde werden durch Filtration entfernt.Sodium aluminate solution, 10% by weight, produced from anhydrous technical grade sodium aluminate, Sigma-Aldrich, and deionized water. A few insoluble residues are removed by filtration.

LUDOXĀ® SM 30, Grace, ist eine wƤsserige, mit NaOH stabilisierte, kolloidale Silicadispersion mit einer PartikelgrĆ¶ĆŸe von 8 nm und einem Gehalt an SiO2 von 30 Gew.-%.LUDOXĀ® SM 30, Grace, is an aqueous, NaOH-stabilized, colloidal silica dispersion with a particle size of 8 nm and a SiO 2 content of 30% by weight.

LUDOXĀ® HS 40, Grace, ist eine wƤsserige, mit NaOH stabilisierte, kolloidale Silicadispersion mit einer PartikelgrĆ¶ĆŸe von 12 nm und einem Gehalt an SiO2 von 40 Gew.-%.LUDOXĀ® HS 40, Grace, is an aqueous, NaOH-stabilized, colloidal silica dispersion with a particle size of 12 nm and an SiO 2 content of 40% by weight.

LUDOXĀ® CL, Grace, ist eine wƤsserige Dispersion von mit AI umhĆ¼llten, kolloidalem Silica mit 22 nm PartikelgrĆ¶ĆŸe. Der pH ist 3,5 - 4,5, der Feststoffgehalt 39 - 43 Gew.-%.LUDOXĀ® CL, Grace, is an aqueous dispersion of Al-coated, colloidal silica with a particle size of 22 nm. The pH is 3.5-4.5, the solids content 39-43% by weight.

Mittel zur OberflƤchenmodifizierungSurface modification agents

  • OM1: 2-[Methoxy(polyethyleneoxy)6-9propyl] trimethoxysilanOM1: 2- [methoxy (polyethyleneoxy) 6-9 propyl] trimethoxysilane
  • OM2: Hydrolysat aus 3-Glycidyloxypropyl-Trimethoxysilan gemƤƟ Beispiel 1, EP-A-832911 OM2: hydrolyzate of 3-glycidyloxypropyl-trimethoxysilane according to Example 1, EP-A-832911
  • OM3: DYNASYLANĀ® GLYMO, Evonik IndustriesOM3: DYNASYLANĀ® GLYMO, Evonik Industries
  • Wasser: es handelt es sich um vollentsalztes Wasser; Natronlauge: 25 Gew.-% NaOH; SalzsƤure: 20 Gew.-% HClWater: it is completely demineralized water; Sodium hydroxide solution: 25% by weight NaOH; Hydrochloric acid: 20% by weight HCl
Beispiel 1 (erfindungsgemƤƟ)Example 1 (according to the invention)

Zu einer verdĆ¼nnen Natriumaluminatlƶsung aus 10 g VE-Wasser und 2,37 g der filtrierten Natriumaluminatlƶsung werden 40 g AERODISPĀ® W7320 langsam und unter RĆ¼hren zugetropft. Nach der Zugabe lƤƟt man noch 10 Minuten nachrĆ¼hren. Dann gibt man 5,90 g OM2 hinzu. AnschlieƟend wird fĆ¼r 10 Minuten auf 90Ā°C erhitzt und der pH-Wert mit SalzsƤure auf 9 eingestellt.
0,064 mg Al/m2 BET-OberflƤche; dso = 128 nm; StabilitƤt in Referenzlƶsung bei 60Ā°C: 4 Wochen.40 g of AERODISPĀ® W7320 are slowly added dropwise with stirring to a dilute sodium aluminate solution composed of 10 g of deionized water and 2.37 g of the filtered sodium aluminate solution. After the addition, the mixture is stirred for a further 10 minutes. Then 5.90 g of OM2 are added. The mixture is then heated to 90 Ā° C. for 10 minutes and the pH is adjusted to 9 with hydrochloric acid.
0.064 mg Al / m 2 BET surface area; dso = 128 nm; Stability in reference solution at 60 Ā° C: 4 weeks.

Beispiel 2 (erfindungsgemƤƟ)Example 2 (according to the invention)

Zu 10 g Wasser werden 2,19 g der Natriumaluminatlƶsung gegeben. Nun wird unter RĆ¼hren tropfenweise 40 g AERODISPĀ® W 7512 S hinzu gegeben und nach der Zugabe 10 Minuten weiter gerĆ¼hrt. Nun werden 3,1 g OM3 tropfenweise hinzugegeben und unter rĆ¼hren auf 90Ā°C aufgeheizt. Nach 10 Min lƤƟt man auf Raumtemperatur abkĆ¼hlen und der pH-Wert wird mit SalzsƤure auf 9 gestellt.
0,064 mg Al/m2 BET-OberflƤche; dso = 109 nm; StabilitƤt in Referenzlƶsung bei 60Ā°C: 9 Wochen2.19 g of the sodium aluminate solution are added to 10 g of water. 40 g of AERODISPĀ® W 7512 S are then added dropwise with stirring and stirring is continued for 10 minutes after the addition. 3.1 g of OM3 are then added dropwise and the mixture is heated to 90 Ā° C. while stirring. After 10 minutes, the mixture is allowed to cool to room temperature and the pH is adjusted to 9 with hydrochloric acid.
0.064 mg Al / m 2 BET surface area; dso = 109 nm; Stability in reference solution at 60 Ā° C: 9 weeks

Beispiel 3 (erfindungsgemƤƟ)Example 3 (according to the invention)

Zu 10 g Wasser werden 2,19 g der Natriumalumintlƶsung gegeben. Nun wird unter RĆ¼hren tropfenweise 40 g AERODISPĀ® W 7512 S hinzugegeben und nach der Zugabe 10 Minuten weiter gerĆ¼hrt. Nun werden 6,8 g OM1 tropfenweise hinzugegeben und unter RĆ¼hren auf 90Ā°C aufgeheizt. Nach 10 Min lƤƟt man auf Raumtemperatur abkĆ¼hlen und der pH-Wert wird mit SalzsƤure auf 9 eingestellt.
0,064 mg Al/m2 BET-OberflƤche; dso = 111 nm; StabilitƤt in Referenzlƶsung bei 60Ā°C: 3 Monate2.19 g of the sodium alumint solution are added to 10 g of water. 40 g of AERODISPĀ® W 7512 S are then added dropwise with stirring and stirring is continued for 10 minutes after the addition. 6.8 g of OM1 are then added dropwise and the mixture is heated to 90 Ā° C. while stirring. After 10 minutes, the mixture is allowed to cool to room temperature and the pH is adjusted to 9 with hydrochloric acid.
0.064 mg Al / m 2 BET surface area; dso = 111 nm; Stability in reference solution at 60 Ā° C: 3 months

Beispiel 4 (erfindungsgemƤƟ)Example 4 (according to the invention)

Zu 10 g Wasser werden 3,64 g der Natriumalumintlƶsung gegeben. Nun wird unter RĆ¼hren tropfenweise 40 g AERODISPĀ® W 7520 N hinzu gegeben und nach der Zugabe 10 Minuten weiter gerĆ¼hrt. Nun werden 6,8 g OM1 tropfenweise hinzugegeben und unter RĆ¼hren auf 90Ā°C aufgeheizt.3.64 g of the sodium alumint solution are added to 10 g of water. 40 g of AERODISPĀ® W 7520 N are then added dropwise with stirring and stirring is continued for 10 minutes after the addition. 6.8 g of OM1 are then added dropwise and the mixture is heated to 90 Ā° C. while stirring.

Nach 10 Min lƤƟt man auf Raumtemperatur abkĆ¼hlen und der pH-Wert wird mit SalzsƤure auf 9 gestellt.
0,064 mg Al/m2 BET-OberflƤche; dso = 101 nm; StabilitƤt in Referenzlƶsung bei 60Ā°C: 4 WochenAfter 10 minutes, the mixture is allowed to cool to room temperature and the pH is adjusted to 9 with hydrochloric acid.
0.064 mg Al / m 2 BET surface area; dso = 101 nm; Stability in reference solution at 60 Ā° C: 4 weeks

Beispiel 5 (erfindungsgemƤƟ)Example 5 (according to the invention)

Es werden 400 g Wasser vorgelegt und mit Hilfe eines Dissolvers 45,5 g der Natriumaluminatlƶsung und 200 g der Dispersion von kaliumdotierter KieselsƤure eingearbeitet. Dieses wird insgesamt 4 mal durchgefĆ¼hrt, in Summe also 182 g Natriumaluminatlƶsung und 800 g der Dispersion. Mit der letzten Zugabe steigt die ViskositƤt stark an. Nun werden OM1 unter RĆ¼hren hinzu gegeben wobei die Dispersion wieder dĆ¼nnflĆ¼ssig wird. Nun wird auf 90Ā°C aufgeheizt und fĆ¼r 30 Minuten die Temperatur gehalten. Nach dem AbkĆ¼hlen auf Raumtemperatur wird mit SalzsƤure ein pH von 9 eingestellt.
0,128 mg Al/m2 BET-OberflƤche; dso = 72 nm; StabilitƤt in Referenzlƶsung bei 60Ā°C: 4 Wochen400 g of water are initially introduced and 45.5 g of the sodium aluminate solution and 200 g of the dispersion of potassium-doped silica are incorporated with the aid of a dissolver. This is carried out a total of 4 times, a total of 182 g of sodium aluminate solution and 800 g of the dispersion. With the last addition, the viscosity increases sharply. OM1 are then added with stirring, the dispersion becoming thin again. It is now heated to 90 Ā° C. and the temperature is maintained for 30 minutes. After cooling to room temperature, the pH is adjusted to 9 with hydrochloric acid.
0.128 mg Al / m 2 BET surface area; dso = 72 nm; Stability in reference solution at 60 Ā° C: 4 weeks

Beispiel 6 (Vergleichsbeispiel)Example 6 (comparative example)

Es werden zu 10 g Wasser werden 1,185 g der Natriumaluminatlƶsung gegeben. Nun werden 10 g AERODISPĀ® W 7320 N langsam und unter RĆ¼hren hinzugegeben. Nun folgt wieder eine Zugabe von 1,185 g der Natriumaluminatlƶsung und 10 g AERODISPĀ® W 7320 N. Dieses Procedere wird noch zweimal wiederholt, so dass insgesamt 4,74 g der Natriumaluminatlƶsung und 40 g AERODISPĀ® W 7320 N eingesetzt werden. AnschlieƟend wird die erhaltene Dispersion 30 Minuten bei 85Ā°C gealtert.1.185 g of the sodium aluminate solution are added to 10 g of water. Now 10 g of AERODISPĀ® W 7320 N are added slowly and with stirring. This is followed by the addition of 1.185 g of the sodium aluminate solution and 10 g of AERODISPĀ® W 7320 N. This procedure is repeated twice so that a total of 4.74 g of the sodium aluminate solution and 40 g of AERODISPĀ® W 7320 N are used. The dispersion obtained is then aged at 85 Ā° C. for 30 minutes.

Nach Zugabe von 7,36 g OM1 zugegeben und es wird noch weitere 15 Minuten bei 85Ā°C gerĆ¼hrt. Nach dem AbkĆ¼hlen auf Raumtemperatur wird mit SalzsƤure ein pH von 9 eingestellt.
0,128 mg Al/m2 BET-OberflƤche; dso = 119 nm; StabilitƤt in Referenzlƶsung bei 60Ā°C: 1 WocheAfter 7.36 g of OM1 have been added, the mixture is stirred at 85 Ā° C. for a further 15 minutes. After cooling to room temperature, the pH is adjusted to 9 with hydrochloric acid.
0.128 mg Al / m 2 BET surface area; dso = 119 nm; Stability in reference solution at 60 Ā° C: 1 week

Beispiel 7 (Vergleichsbeispiel)Example 7 (comparative example)

Zu 40 g Wasser werden unter RĆ¼hren 1 g der Natriumaluminatlƶsung und dann 5 g eines Kieselsols, hergestellt aus 20 g LudoxĀ® HS 40 von Grace und 20 g Wasser, zugegeben. Diese schrittweise Zugabe wird so oft wiederholt bis insgesamt 8 g der Natriumaluminatlƶsung und 40 g des Kieselsoles hinzugeben wurden. Es entstehen bei der Zugabe der Natriumaluminatlƶsung kleine Flocken, die sich nach Zugabe der Dispersion wieder langsam auflƶsen. Nun wird bei 70Ā°C fĆ¼r 3 Stunden weiter gerĆ¼hrt.1 g of the sodium aluminate solution and then 5 g of a silica sol, prepared from 20 g of LudoxĀ® HS 40 from Grace and 20 g of water, are added to 40 g of water with stirring. These The gradual addition is repeated until a total of 8 g of the sodium aluminate solution and 40 g of the silica sol have been added. When the sodium aluminate solution is added, small flakes are formed which slowly dissolve again after the dispersion has been added. The mixture is then stirred at 70 Ā° C. for 3 hours.

AnschlieƟend werden 10 g OM2 hinzugegeben und auf 90Ā°C aufgeheizt. Nach 10 Minuten bei 90Ā°C lƤƟt man auf Raumtemperatur abkĆ¼hlen und stellt den pH-Wert mit SalzsƤure auf pH 9 ein. 0,127 mg Al/m2 BET-OberflƤche; StabilitƤt in Referenzlƶsung bei 60Ā°C: 3-4 TageThen 10 g OM2 are added and the mixture is heated to 90 Ā° C. After 10 minutes at 90 Ā° C., the mixture is allowed to cool to room temperature and the pH is adjusted to 9 with hydrochloric acid. 0.127 mg Al / m 2 BET surface area; Stability in reference solution at 60 Ā° C: 3-4 days

Beispiel 8 (Vergleichsbeispiel)Example 8 (comparative example)

Zu 67 g AERODISPĀ® W 7512 S werden langsam und unter RĆ¼hren 11,3 g OM1 gegeben. Es tritt zuerst ein ViskositƤtsanstieg auf der aber bei weiterer Zugabe wieder abnimmt. Nun wird mit Natronlauge unter RĆ¼hren ein pH von 11 eingestellt und die Mischung auf 90Ā°C erwƤrmt. Nach 10 Minuten bei 90Ā°C wird abgekĆ¼hlt und mit SalzsƤure ein pH von 9 eingestellt.
StabilitƤt in Referenzlƶsung bei 60Ā°C: 1 Tag11.3 g of OM1 are slowly added to 67 g of AERODISPĀ® W 7512 S while stirring. At first there is an increase in viscosity which, however, decreases again with further addition. A pH of 11 is then set with sodium hydroxide solution while stirring and the mixture is heated to 90.degree. After 10 minutes at 90 Ā° C., the mixture is cooled and the pH is adjusted to 9 with hydrochloric acid.
Stability in reference solution at 60 Ā° C: 1 day

Beispiel 9 (Vergleichsbeispiel)Example 9 (comparative example)

Zu 40 g AERODISPĀ® W 7520 N werden langsam und unter RĆ¼hren 11,3g OM1 zugegeben. Nun wird mit Natronlauge unter RĆ¼hren ein pH von 11 eingestellt und die Mischung auf 90Ā°C erwƤrmt. Nach 10 Minuten bei 90Ā°C wird abgekĆ¼hlt und mit SalzsƤure ein pH von 9 eingestellt.
StabilitƤt in Referenzlƶsung bei 60Ā°C: 1 Tag11.3 g of OM1 are slowly added to 40 g of AERODISPĀ® W 7520 N while stirring. A pH of 11 is then set with sodium hydroxide solution while stirring and the mixture is heated to 90.degree. After 10 minutes at 90 Ā° C., the mixture is cooled and the pH is adjusted to 9 with hydrochloric acid.
Stability in reference solution at 60 Ā° C: 1 day

Beispiel 10 (Vergleichsbeispiel)Example 10 (comparative example)

Zu 100 g einer mit Wasser auf 10 Gew.-% verdĆ¼nnten LUDOXĀ® 30 SM Dispersion werden bei 80Ā°C innerhalb von 3 Stunden 4,3 g OM1 unter RĆ¼hren hinzu getropft. Es wird bei 80Ā°C 6 Stunden weiter gerĆ¼hrt.
StabilitƤt in Referenzlƶsung bei 60Ā°C: 1 TagTo 100 g of a LUDOXĀ® 30 SM dispersion diluted to 10% by weight with water, 4.3 g of OM1 are added dropwise at 80 Ā° C. over the course of 3 hours, with stirring. The mixture is stirred at 80 Ā° C. for a further 6 hours.
Stability in reference solution at 60 Ā° C: 1 day

Beispiel 11 (Vergleichsbeispiel)Example 11 (comparative example)

Zu 249 g LUDOXĀ® HS 40 werden 30 g OM1 gegeben. Die Dispersion wird auf 80Ā°C erhitzt und bei dieser Temperatur 16 Stunden gerĆ¼hrt.
StabilitƤt in Referenzlƶsung bei 60Ā°C: 1 Tag30 g OM1 are added to 249 g LUDOXĀ® HS 40. The dispersion is heated to 80 Ā° C. and stirred at this temperature for 16 hours.
Stability in reference solution at 60 Ā° C: 1 day

Beispiel 12 (Vergleichsbeispiel)Example 12 (comparative example)

26,7 g LUDOXĀ® CL werden mit 13,3 g Wasser auf 20 Gew.-% verdĆ¼nnt. Zu diesem Sol werden langsam und unter RĆ¼hren 13,0 g OM1 zugegeben. Nun wird mit Natronlauge unter RĆ¼hren ein pH von 11 eingestellt und die Mischung auf 90Ā°C erwƤrmt. Nach 10 Minuten bei 90Ā°C wird abgekĆ¼hlt und mit SalzsƤure ein pH von 9 eingestellt.26.7 g of LUDOXĀ® CL are diluted to 20% by weight with 13.3 g of water. 13.0 g of OM1 are slowly added to this sol with stirring. A pH of 11 is then set with sodium hydroxide solution while stirring and the mixture is heated to 90.degree. After 10 minutes at 90 Ā° C., the mixture is cooled and the pH is adjusted to 9 with hydrochloric acid.

Nach zwei Tagen bei 60Ā°C tritt ein wolkiger Niederschlag auf.
0,174 Al/m2 BET-OberflƤche (berechnet aus Angaben des Herstellers)
StabilitƤt in Referenzlƶsung bei 60Ā°C: 2 TageAfter two days at 60 Ā° C a cloudy precipitate appears.
0.174 Al / m 2 BET surface (calculated from the manufacturer's information)
Stability in reference solution at 60 Ā° C: 2 days

Beispiel 13 (Vergleichsbeispiel)Example 13 (comparative example)

26,7 g AERODISPĀ® W 630 werden mit 13,3 g Wasser auf 20 % verdĆ¼nnt. Zu dieser Dispersion werden langsam und unter RĆ¼hren 5,67 g OM1 zugegeben. Nun wird mit Natronlauge unter RĆ¼hren ein pH von 11 eingestellt und die Mischung auf 90Ā°C erwƤrmt. Nach 10 Minuten bei 90Ā°C wird abgekĆ¼hlt und mit SalzsƤure ein pH von 9 eingestellt.
StabilitƤt in Referenzlƶsung bei 60Ā°C: 1 Tag26.7 g of AERODISPĀ® W 630 are diluted to 20% with 13.3 g of water. 5.67 g of OM1 are slowly added to this dispersion with stirring. Now is taking with caustic soda Stirring adjusted a pH of 11 and the mixture heated to 90 Ā° C. After 10 minutes at 90 Ā° C., the mixture is cooled and the pH is adjusted to 9 with hydrochloric acid.
Stability in reference solution at 60 Ā° C: 1 day

Die erfindungsgemƤƟen wƤsserigen Dispersionen der Beispiele 1 - 4 weisen eine sehr gute StabilitƤt in der Referenzlƶsung bei erhƶhter Temperaturen auf. Diese StabilitƤt ist bei den Vergleichsbeispielen 5-13 nicht gegeben.The aqueous dispersions according to the invention of Examples 1-4 have very good stability in the reference solution at elevated temperatures. This stability is not given in Comparative Examples 5-13.

Claims (6)

  1. Aqueous dispersion comprising particles of a surface-modified, pyrogenic hydrophilic silica, characterized in that
    A) the particles of the surface-modified, hydrophilic silica comprise an aluminium atom and a hydrocarbon radical,
    a) the aluminium atom is bonded via an oxygen atom to a silicon atom of the particle surface,
    b) the hydrocarbon radical comprises a silicon atom which is bonded to a carbon atom of the hydrocarbon radical,
    c) possess an average particle diameter d50 in the dispersion of 40 - 200 nm, and
    B) the pH of the dispersion is 8 or more.
  2. Aqueous dispersion according to Claim 1,
    characterized in that
    the fraction of Al in the surface-modified, hydrophilic silica is ā‰¤ 0.15 mg Al/m2 BET surface area.
  3. Aqueous dispersion according to Claims 1 or 2,
    characterized in that
    the carbon content of the surface-modified, hydrophilic silica is 3 - 25 wt%.
  4. Aqueous dispersion according to Claims 1 to 3,
    characterized in that
    the hydrocarbon radical is interrupted by one or more heteroatoms.
  5. Aqueous dispersion according to Claims 1 to 4,
    characterized in that
    the hydrocarbon radical is selected from the group consisting of Si-(CH2)n-Ym-R, the silicon atom being bonded via a carbon atom of the hydrocarbon radical, obtainable using an agent for surface modification selected from the group consisting of
    X4-a[Si-(CH2)n-Ym-R]a, where
    a = 1, 2 or 3;
    X = OH, OCH3, OC2H5, OCH2CH2H3, OCH(CH3)2; Cl,
    n = 1, 2 or 3 and m = 0 or 1,
    Y=-(OCR1R2-CR3R4)o-, o = 1 - 30, R1, R2, R3, R4 = independently of one another H or CH3, - (OCR1R2-CR3R4-CR5R6)p-, p = 1 - 30, R1, R2, R3, R4, R5, R6 = independently of one another H or CH3,
    R, when m = 1, is -H, -CH3, -C2H5, -OH, -OCH3, -OC2H5, -C(=O) OCH3, - C(=O)OC2H5, -O-C(=O)CH3, -O-C(=O)CH3, -O-C(=O)CH=CH2, -O-C(=O)CH=CH(CH3), -C(=O)CH3, - C(=O)H, NH2;
    Figure imgb0006
     and, when m = 0, corresponds to the aforementioned radicals, but without -H, -CH3,-C2H5,
    or is a mixture of the aforementioned radicals R and Y.
  6. Aqueous dispersion according to Claims 1 to 5,
    characterized in that
    in the dispersion, the fraction of water is 50 - 90 wt% and of surface-modified silica is 10 - 50 wt%.
EP16733472.1A 2015-07-10 2016-06-28 Sio2 containing dispersion with high salt stability Active EP3319906B1 (en)

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